Presently, a user of a data processing system, such as a desktop computer or a laptop computer, can use multiple display devices concurrently as the output devices from the data processing system, such as a single desktop computer or a laptop computer. The use of multiple displays allows for a greater display space allowing the user to display more windows or larger windows, etc. Currently, on the Macintosh operating system OS X, two or more display devices, such as liquid crystal displays or plasma displays or CRT displays can be driven by one or more display controllers on a data processing system. Currently in OS X, the dock, which is a form of an application control region, exists on a primary display and a system wide menu bar exists also on the primary display while any other displays will not include the dock and will not have a menu bar. The other displays can present a background image which is part of a desktop as is known in the art. A user can move a window from one display to another display and vice versa, and in doing so the window will appear to move across the displays. When a window straddles between two displays, it appears the same on both displays (ignoring any effect caused by a mismatch in display settings or display characteristics which can cause differences in color or luminance as a result of the mismatch between the displays).